1. Field of the Invention:
The present invention relates generally to damper mechanisms, and more particularly to a piston-cylinder type air damper for damping the downward movement of, for example, an automobile glove compartment door which rotates about a pivot so as to open the glove compartment gently.
2. Description of the Prior Art:
Japanese Utility Model Public Disclosure No. 2-58137, for example, discloses a piston-cylinder type air damper comprising a cylinder having an open end and a closed end, a piston having a head slidably disposed in contact with the inner wall of the cylinder, a piston rod extending axially from the piston head and outwardly from the open end of the cylinder, and a cap fitted upon the open end of the cylinder and permitting the piston rod to penetrate therethrough.
In the prior art air damper, the piston head is provided with a two-way vent valve, the closed end of the cylinder is connected to a structural member of the passenger compartment, and the end of the piston rod disposed opposite to the piston head is connected to the glove compartment door. With this arrangement, when the piston head is caused to slide within the cylinder toward the open end thereof for the purpose of opening the glove compartment door, the air passing through the vent valve is controlled by means of the vent valve so as to damp the opening movement of the glove compartment door. Conversely, when the piston head is slidably moved within the cylinder toward the closed end thereof for closing the glove compartment door, the air is allowed to freely pass through the two-way vent valve so as to facilitate the closing movement of the glove compartment. The cap for closing the open end of the cylinder of the prior art air damper is molded from a suitable hard synthetic resin such as, for example, POM (polyoxymethylene), is provided at the center thereof with a guide hole which has a sectional profile slightly larger than that of the piston rod, and thereby permits the piston rod to penetrate therethrough so as to guide the sliding movement of the piston. For this reason, peripheral portions of the piston rod collide against the edge of the guide hole during operation of the automobile and produce a rattling sound. In order to prevent this rattling noise, it is necessary to attach a felt piece to the cap with suitable adhesive or tape so that the piston rod will collide against the felt piece. This attaching step is troublesome and increases the number of steps required for assembling the damper.